This invention relates to the metered injection of viscous chemical additives into a liquid flowing in a pipeline. More particularly, a compatible low viscosity liquid is used to assist the suction side of an injection pump.
There are many instances where a chemical additive is injected in a metered manner into a liquid flowing in a pipeline. For manufacturing, shipping, storage and other reasons, it is sometimes desirable to use a viscous liquid or semi-liquid additive, for example, injection of a viscous drag reduction agent into an oil pipeline. But the injection of a viscous additive creates several problems. Sometimes, it is difficult to pump a viscous additive with off-the-shelf pumps. When a special pump is required, there are the inherent problems for maintaining, repairing and replacing the pumps, especially in remote areas. Regardless of the type of pump used, it is difficult for the injection system to accurately measure and the pump to consistently inject the proper amount of a viscous additive.
One method of aiding the flow of a viscous additive is to use a gas pressurized container; but there are limits on the gas pressure that may be applied without rupturing the container and sometimes without interferring with the calibration of the metering pump.
The effectiveness of an additive usually depends on its solution or dispersion in the pipeline liquid in a relatively fast manner. The mixing forces caused by flow of the liquid in the pipeline are sometimes insufficient to solubilize or disperse the additive in the required time.
It is the purpose of this disclosure to provide a viscous additive injection system that increases the suction side efficiency of an additive injection pump and that may also assist in the rate of solution or dispersion of the additive in a pipeline liquid.